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Fluctuations in the scrape-off layer and edge plasma of the COMPASS tokamak
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SYSNO ASEP 0501889 Document Type C - Proceedings Paper (int. conf.) R&D Document Type Conference Paper Title Fluctuations in the scrape-off layer and edge plasma of the COMPASS tokamak Author(s) Seidl, Jakub (UFP-V) RID
Jiráková, Kateřina (UFP-V)
Adámek, Jiří (UFP-V) RID, ORCID
Grover, Ondřej (UFP-V) ORCID
Horáček, Jan (UFP-V) RID, ORCID
Hron, Martin (UFP-V) RID, ORCID
Vondráček, Petr (UFP-V) RID, ORCIDNumber of authors 7 Article number P1.1103 Source Title 45th EPS Conference on Plasma Physics, 42A. - Mulhouse : 45th EPS Conference on Plasma Physics, 2018 - ISBN 9781510868441 Pages s. 481-484 Number of pages 4 s. Publication form Online - E Action 45th European Physical Society Conference on Plasma Physics Event date 02.07.2018 - 06.07.2018 VEvent location Praha Country CZ - Czech Republic Event type WRD Language eng - English Country FR - France Keywords plasma ; tokamak ; turbulence Subject RIV BL - Plasma and Gas Discharge Physics OECD category Fluids and plasma physics (including surface physics) R&D Projects GA16-25074S GA ČR - Czech Science Foundation (CSF) 8D15001 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) LM2015045 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) Institutional support UFP-V - RVO:61389021 EID SCOPUS 85057874967 Annotation We have identified two distinct types of turbulent fluctuations in COMPASS plasmas, the high-frequency edge oscillations and low-frequency SOL blobs. The transition region is localized in the near SOL, where both types spatially overlap and interact and the radial particle transport gradually transfers from high to low frequencies. Even though skewness of isat fluctuations is positive even inside LCFS, distinguishable Gamma-distributed PDF, formed by the low-frequency fluctuations, arises in the near SOL. This supports, together with turbulence spreading rate being positive in the near SOL but negative in the edge, the picture presented in [3] that most of the fluctuations that form a positive skewness in the edge region disappear around LCFS and new blobs are formed in the near SOL. Further, we cannot confirm the assumption that the blobs are generated randomly according to a Poisson process. Oscillations of all measured quantities, incl. radial particle flux, in the near SOL are peaked around ∼13 kHz. This seems to correspond to a poloidally rotating structure with a rather large poloidal wave-length ∼ 15 − 20 cm, that at least partly modulates blob generation. Nevertheless, we note that time separation of blobs becomes more random further in the SOL, possibly due to differences in their individual propagation. These observations hold for diverted plasmas, but the situation may be different in limited low-elongation plasmas where the radius of zero skewness was observed to be shifted significantly (several cm) inwards, compared to diverted configuration, and Gamma-like PDF is detected even inside the LCFS. Study of these plasmas is ongoing. Workplace Institute of Plasma Physics Contact Vladimíra Kebza, kebza@ipp.cas.cz, Tel.: 266 052 975 Year of Publishing 2019 Electronic address http://ocs.ciemat.es/EPS2018PAP/pdf/P1.1103.pdf
Number of the records: 1